A lock cylinder, as described, for example, in Austrian Pat. No. AT 341 901, can comprise a cylinder housing and a cylinder core having at least one, and usually a plurality, of rotatable magnetic tumblers supported therein.
In the cylinder core at least one axially slidable bolt member is provided, whose slidability is controlled by the rotatable magnetic tumblers, and the bolt member has at least one projection, preferably a plurality of projections, directed toward the exterior of the lock cylinder. The inside wall of the cylinder housing has at least one circular groove and an axially running groove.
The circular grooves are located axially, so that in an axially shifted position of the bolt member, in which contacting elements protruding toward the inside of the lock cylinder lie in notches of the rotatable magnetic tumblers, i.e. when the correct key is inserted, the previously restrained projections of the locking element are in a position permitting rotation of the cylinder core.
Other such lock cylinders are described in, for example, the Austrian Pat. No. AT-PS 357 430. By comparison with these systems, it would be advantageous to reduce the forces operating, during faulty or incorrect locking, on the rotatable magnetic tumblers of the lock cylinder, in order to prevent probable damage to the rotatable magnetic tumblers, and to be able to select reduced dimensions for the contacting elements and other components and thus to increase the mechanical precision of the lock.
Furthermore it would also be an advantage to reduce the influence of the environment, including that of weather, dust, corrosive material, and the like, on the relatively movable components of the lock cylinder and the cylinder core.
In the lock cylinder structure according to the Austrian Pat. No. AT-PS 357 430 a bolt member is used, which is held under an elastic restoring force form one side by means of a spring or the like, and is pressed with a control tip against the control surface of a locking ring. The operation of the locking ring as a force-limiting coupling depends on its mechanical precision.
For the release of the force-limiting coupling comparatively large applied forces are required, which act disadvantageously on the rotatable magnetic tumblers.
With faulty mounting, bending and compression of the locking ring can occur, so that precise operation can not be maintained.
By comparison with the device of Austrian Pat. No. AT-PS 357 430, it would be advantageous to provide a positively actuated control of the bolt member and its shifting, which is independent of the sliding force provided by a spring.